Safety manhole cover lock



SAFETY MANHOLE COVER LOCK Filed June 6, 1950 SEN wl/fw? MH I l l.

5 INVENTOR.

United States Patent Oce 2,693,100 Patented Nov. 2, 1954 SAFETY MNTHQLE CGVER LOCK A:Charles B. Wiegel, rchicago, lll.

.Application June .6, 1950, SerilNm 1166,4.05

'11 Claims {(Cl. '70-168) This :invention relates to improvements Yin manhole .covers, an bject being 'to :provide a safety `manhole kcover largely to T prevent "accidents 'to children, :Whose curiosity, whetted perhaps by admonitions to `the contrary, Vleads them to pry 'up .and 'remove ordinary manhole covers to disclose the mysteries beneath, 'with the result that they are apt to Tall vin Aand vbe injured .or drowned.

The-unauthorized opening of such manholes is not confined to lcli-ldren, "however. r 'Ihey are `at vtimes used 'for the surreptitious disposal of trash :or articles, :and sometimes ffor the concealment and Adisappearance of 'evidence o'f crime.

Accordingly, it is ran'objectolthe invention to provide a safety `manhole cover which, when once `satisfactorily secured in place, Acannot 4be removed by `pries 'or ordinary tools applied or inserted around the edge of the cover or otherwise, l'but can only rbe lifted lor vremoved 'from uthe manhole rim -or r-'ing lor `opening by iirst `unlocking V"the same, las by a special Akey.

Other objects Iare to 'provide such 'a safety ymanhole cover in "which Ythe lkey Vcannot be removed therefrom without placing the mechanism in locking position, vwhich tends *to 'prevent loverlooking fthe locking of 'the :cover when Tit is applied to the manhole rand the positioning of the cover -in the manhole Aopening inthe yabsence of lthe key in the cover. 'The 'key may also 'form -a .convenient handle to `assist in rhandling 'and manipulating the 'cover in applying fand removing `'the same.

Other objects "of :the invention are -to provide 'such 'a safetyfmanhole over'wliich is adapted for use with manholes fof ystandard -type and which Eis sturdy v'and strong, simple in construction and operation, and relatively inexpensive.

-.Further objects and :advantages will appear from *the description and claims tto'fo'llow, 'in connection with ithe accompanying drawing .which illustrates, iby 'way -of Jeitampl'e ibut mot of limitation, an Y'embodiment of -the 3invention, fand :in 'which :drawing:

Figure l1 is fa vertical section 'through a .typical manhole 'with fthe `cover Yin e-pl'ace fthereon, vsaid section being taken onfthelline ll-ltof Fig. 2';

:is a View taken :on the plane v4indicated by the line .A2-2 .in .Fig. l :and looking :upwardly 1to fshow the bottom of :the cover in vrelation -to the manhole;

Eig. :3 :is ravertical section 'on the 'line 3-3 of 'Fig. 2, through 'the :cover-hdlding and :locking mechanism, lthe parts being :shown Vright :side rup;

.Fig. 4 tis :a fp'lan yview loi Y'the Tlocking keyhole in the cover'takenon the yli11e14--4 `of Fig. '3;

Fig. r5 is :a horizontal Isection on the 'line 5-5 fof Fig. 3 fand 'showing fthe position of the key in "the unlocked position ofthe coverllocking means;

-lFig. 6 is aperspect'ive view lof'the"`t1racket on the :underside of the .cover plate 'for supporting the locking mechanism; and

"Fig. .7 is a Ip,er. spectiv.e detail view of .one .of .the other locking brackets.

Referring to -these views, particularly Figs. .l and .2, the usual manhole for catch basins, draimpits .and sewer connections comprises a relatively large :circular opening 10 in aconcretefslab .11 `:which :islaid andzsecuredionztop of .the brick wall 12 .lining :the .-hole .in ;the :ground tand leading to thecatch basin .orthe like below. Thewvall is larger -in ydiameter `than the :said ropening :and :the inwardlyyprojectingportion lof tthe @slab varound the-'opening 'terms y resistance to pryingaup the ledge fof the manhole. vThe concrete .slab imayezrtend outwardly as fa-.r as desired, .and its upper .surface is 'usually substantially at the surrounding ground level.

The opening 10 surrounded by a depression or .recess 1'5 to receive `the peripheral edge .of a circular cover plate 16 'the upper surface 4of which, when 'the cover is in position to cover the opening, may A'be substantially ush with the top of the .concrete slab. .A metal ring is sometimes embedded 1in the concrete to form .the edge of 'the `opening 110, but this Icover is .applicable thereto in the same manner as 'herein shown and described.

The cover 16 may be -of the `usual castmetal type having preferably a roughened `upper surface and such .legends as may be desired thereon, and is of considerable weight.' vAn annular raised rib 19 maybe formed on the lower side to :assistfin centering lthe cover in 'the manhole opening. The .edge of the .cover ts freely into the annular depression '15 -of the manhole ledge.

ln order to prevent removal o'f the cover from its ;p o sition when in place on the manhole by prying .under its edge or the like, a plurality of holders or clamps are provided on 4the underside ojf Ithe cover which engage under the manhole Yring and lock it .in lplace.

Two, preferably, of these locking holders 2.0, 2B., as seen in Fig. L2, are located on one side o'f the center of thecover -and another, 21, .on the other side ofthe center. The holders j2'0.are fixed, but the holder 21, ,or the man hole ledge gripping part thereof., may be withdrawnrrom its ledge-engaging position, as 'later explained, by a suitab'le key operated -from the top side of the cover.

Each of the 'holders' or clamps 20 comprises a .metaly bracket '22, "the oojt of which 'is secured, as "by screw bolts '23, to the underside lof the cover and an angle member '24 'bolted to 'the bracket 22 by bolts extending through anadjustingslot, or slots, '25 therein, Fig. '7, and having .a leg '26 extending under and engaging ,the lower edge Aof 'the manhole ledge. 'The object of .the fixed adjustment in this bracket combination is to ,accommodate the holders to ledges having varying thicknesses.

'The holders :or clamps 20 are spaced apart circumferentially 'of the cover to give spaced locking tpoints with the manhole ledge for greater strength and ,for tgreater eiorts at the sides, and to assist in applying the cover to the manhole opening.

The .combined angular or 2 bracket 22, 24, .26 is thus comparatively strong and: rigid to Yprevent raising .the cover -a't the edge, jyet vwith sufficient resiliency to Apermit the arms or legs 26 with 'their slightly .downturned `ends to 'give sufficiently to permit .the cover to `be ,slid or turned into 'its position in the manhole; and conversely, when withdrawing the cover, by the reverse Amovements the larms .26 -will `give `suciently to lenable the cover to 'be tipped 'up Aand withdrawn.

l.The clamp `or holder T21 opposite 'the clamps .20., .which may :be withdrawn fromcngagement with the :manhole ledge ior the kplacement and removal of .the .cover and shown in an enlarged scale :in Eigs. 3 to .6, comprises a depending bracket T30, 'Fi'g. .6, bolted as shown ynl' otherwise v.secured fto 'the untlersicle .of the cover. vA Ahorizontal member .31 .is punched vand bent trom vthe vertical portion of lthe 'bracket 30 and its flower fend is bent into another suitably -positioned horizontal `sulzzporting 'meuk ber 32. .A horizontal Vslotll yand vertical communicating slot or notch 34 are 'formed 'infbracket 31).' .Aligned holes are formed 'in .the two members 31 xand 32, which in Vturn w.vertically align with the circular portion of .the keyhole 35 formed 'in ,the cover plate 16.

This 'locking clamp or holder '21 (includes a vertically movable .stem Ior shaft 36 ,passing up through the apertures in the Lmembers `32 .and 31 of the bracket 30 and into .the keyho'leS .in the .c ovcr, terminating :at .its .upper end substantially .flush with .the upper .sur-.face of Lthe cover 1'6 when in its kuppermost ,position 4'Att its lower end the s'tem36 hasrigidly secured thereto, as by .rivetting or otherwise, .the horizontal locking, clamping .or holding member '37 corresponding to arms 26 .of the .clamps 20 .in .the .sense :thatit .is .adapted to engage under ,the manhole :ledge to .hold `the cover .in fits Aclosed position. A -coiled sspring .38 surrounds stern .3.6 and #rests on the lower znflomberV S2 of the y.bracket .30. Its :upper end engages 'the lower siideoftthe ,projecting ends of a cross pin 39 `extending .transversely through and latlxed in the stem 36. This is a relatively strong spring and constantly urges the stem 36 toward its uppermost position in which the horizontal holding member 37 may engage the lower face of the manhole ledge or the lower face of the bracket member 32 where the cover is not on the manhole. In the position of Fig. 3, which, as will appear, is the locking or clamping position of the holder 37, the inner upwardly bent end 40 thereof stands atly against the face of the bracket 30 and prevents turning of the lock arm 37 from its locking position. The spring 38 also accommodates any variation in thlckness of the manhole ledge, such as may be taken care of by the slot adjustment of the clamps or holders 20 on the other side of the center of the cover.

In order to push the stem 36 of the lock down and to turn it a partial turn to free the locking arm 37 from beneath the manhole ledge so that the cover maybe raised at that edge from its seat preparatory to removing it entirely from the manhole, 42, Fig. 3, is provided. This key is tubular and 1s adapted to be pushed down over the stern 36 of the clamp through the keyhole 35 in the cover plate and through the opening in the member 31 of the bracket Again, should the key be removed while the cover is not on the manhole, the cover cannot be again seated in its place on the manhole, because in removing the key the locking bar 37 has been swung outwardly to its locking position and would prevent the seating of the cover. It is necessary in such case to reinsert the key in the cover and turn the arm 37 to its unlocked position before the cover can be reseated on the manhole.

Without further elaboration, the foregoing will so fully explain the gist of the invention that others may, by applying current knowledge, readily adapt the same for use under varying conditions of service, without eliminat- Y ing certain features which may properly be said to cona suitable key or handle 30. The lower end of the key is slightly bevelled, preferably as indicated, to aid in its ready engagement over the end of the stem and its passage downwardly over it, and is provided with opposed recesses 43 formed to engage over and receive the projecting ends of cross pin 39 in the stem 36. By this means the stem 36 of the lock may be pushed downwardly and turned to free the arm 37 from the manhole ledge so that the cover is free to be lifted from its seat at that edge, and then be withdrawn to free the clamps or holders from the manhole ring at the opposite edge of the cover, so that the cover may be completely removed. The cover may be applied to the manhole by the reverse operations of resting it edgewise at its rim between holders on the ledge seat and tipping and lowering its opposite edge downwardly whereby to slide the holders 20 under the manhole ledge, and seating the cover in its peripheral seat. The key may then be pushed down and turned to swing the locking arm 37 out under the manhole ledge. When the key is released and withdrawn. the arm 37 is raised by the spring and engages the ledge as described, and the cover is held against unauthorized removal.

Further to safeguard the cover against being tampered with and to ensure its being locked in position, the key may be provided with a pin 44 rigidly secured thereto,

which when the key is pushed downwardly passes through I the slot portion 45 of the keyhole 35. When the key and stem are so pushed down to the dotted-line position of Fig. 3 and turned, the pin 45 engages under the cover and the key cannot then be withdrawn. time the upturned end 40 of the locking arm 37 is below the member 32 of the bracket 30 and can be turned. Ordinarily, to be sure the locking arm 37 clears the inside of the manhole ring, the key is turned to the At this mid-position, that is, 180, which may be termed the unlocked position of the clamp. At this time the end of the pin 44 on the key 42 enters the horizontal slot 33 of the bracket 30 as the key is turned and then jumps up into the vertical notch 34 of said slot, on account of the upward thrust of the spring 38, assuming at this time the key is not being heavily pushed downwardly.

This prevents the key from being turned in the cover, and since it cannot be withdrawn from the cover and it and the parts associated therewith are of rugged and strong construction, the key makes a convenient handle for assisting in lifting the cover and handling and manipulatina it in applying it to and removing it from the manhole. At this time also the upturned end 40 of the locking bar 37 has swung around and slides up along the Souared end of the member 32 of bracket 30. so that the locking7 arm 37 itself is additionally locked in its off or unlocked position and cannot be turned.

With lthe key projecting up from the cover, the cover is not likely to be forgotten or left in that condition after putting it in place on the manhole; but in order to remove the key it must be pressed down and turned to the original position, where the pin 44 can be drawn out the slot 45 of the keyhole, and in so doing the clamping or locking bar 37 is turned to locking position, as in Fig. 3, and the cover is locked in place. Thus, the locking of the cover is not forgotten or the cover intentionally left unlocked and the key removed.

stitute the essential items of novelty involved, which items are intended to be defined and secured by the following claims.

I claim:

l. A safety manhole cover for peripherally seating on the thick-walled ledge of a manhole and having locking devices on the underside of the plate for engaging under the ledge to resiliently lock the cover in its seat, one of said devices having a laterally extending locking member mounted to be turned outwardly into locking position under such an adjacent ledge or inwardly into unlocked position within the vertical limits of the ledge, the c over having a keyhole above the said member, a key for insertion in said hole for so turning said member into its locking or unlocking position, the key, hole and member being interrelated to prevent removal of the key from the cover when the said member is in other than its locking position, and spring-operated means to prevent turning of the key in the final unlocked position of the parts.

2. A safety manhole cover comprising a coverplate adapted to be peripherally seated on the thick-walled ledge of a manhole, locking devices on the underside of said plate having laterally and outwardly extending arms to resiliently engage under the surrounding ledge to lock the coverin place on its said seat, one of said devices having a vertical stern carrying at its lower end its said locking arm, the cover having a keyhole into which the upper end of said stem projects, a spring on the stem urging it upwardly, stop means to prevent rotation of the stem and locking arm when in locking position, and a key formed to iit into said keyhole to engage and grip the said stem and serving when manually pressed to depress the stem and its arm to free the said stop means and by rotation to turn the stem and arm into unlocking position.

3. A safety manhole cover for thick-walled .manholes including a locking device mounted on the underside of the cover, said device including a bracket, a vertical stem in said bracket having its upper end projecting into a keyhole formed in the cover and a laterally extending clamping member at its lower end to engage under the manhole ledge for clamping the cover in place on the manhole, a spring tensioned to lift said stem and member into clamping position, a projecting stop on said stern, and a key having a hollow shank adapted to be inserted in said hole over said stem and having engaging recesses in its end for said stem stop, the key operating to depress and rotate said stem to clamp and unclamp the same.

4. A safety manhole cover for thick-walled manholes including a locking device mounted'on the underside of the cover, said device including a vertical stem having its upper end projecting into a keyhole formed in the cover and a laterally extending clamping member at its lower end to engage under the manhole ledge for clamping the cover in place on the manhole, locking means for said stem and member in both clamping and unclamping positions, a spring. tensioned to lift said stern and member into clamping and locking position, a projecting stop on said stem, a key having a hollow shank adapted to be inserted in said hole over the said stem and having stem stop engaging recesses in its end, the key operating to depress and rotate said stem to lock and unlock and clamp and unclamp the same, the keyhole having a slot extension in definite relation to the locking position of the stem and clamping member, and a projection on the shank of the key passing through said slot when the key is inserted in the keyhole and' depressed, said projection engaging under the cover when the key is so depressed and turned and thereby prevent` ing the withdrawal of the key from the cover except when the clamping member is in the clamping position.

5. A removable safety cover for a manhole in a thick-walled top slab of a subterranean catch basin or the like, comprising a cover plate having peripheral support on the top of the circumferential ledge of the manhole in the top slab, vertical brackets secured to the bottom of said plate and extending substantially below the same, and clamping arms mounted at the lower ends of said brackets and substantially spaced from said plate, said arms extending horizontally outward to resiliently engage under and hold to the lower side of said manhole ledge to clamp and hold the cover in place on the top of the slab and manhole, the said brackets at one side of the center of the plate having xedly adjustable vertical legs, the horizontal clamping arms therefrom being resilient to enable them to be radially slipped under and off the ledge in hingedly applying the cover to the manhole and removing the same therefrom and exerting a clamping action on the ledge when the cover is seated thereon, a vertically reciprocating upwardly spring-pressed rotatable stem in the bracket on the other side of the center of the plate, the clamping arm of that bracket being rigidly secured to the lower end of said stem, stop means preventing rotation of said stem and arm in the raised clamping position, the cover plate having a keyhole, the upper end of said stem being accessible through said keyhole, and a separable key insertable through the keyhole and engageable with said stem and manually operable to depress and free the stem and arm from said stop means and to rotate the same between said positions.

6. A removable safety cover for a manhole in a thickwalled top slab of a subterranean catch basin or the like, comprising a cover plate having peripheral support on the top of the circumferential ledge of the manhole in the top slab, vertical brackets secured to the bottom of said plate and extending substantially below the same, and clamping arms mounted at the lower ends of said brackets and substantially spaced from said plate, said arms extending horizontally outward to resiliently engage under and hold to the lower side of said manhole ledge to clamp and hold the cover in place on the top of the slap and manhole, one of said brackets having a vertical portion corresponding to the thickness of the said ledge and with horizontally projecting bottom and intermediate portions having vertically aligned apertures therein, the cover having a keyhole in line with said apertures, a vertically movable and rotatable stem mounted in said apertures, the clamping arm of the said bracket being secured to the lower end of said stem beneath the said bottom portion of the bracket, a coiled spring on said stem urging it upwardly, t,

interengaging parts on the arm and the said bottom portion in the clamping position of the arm and locking same against rotation, and a separable key insertable through said keyhole to grip the said stem to depress and unlock the arm and to rotate it.

7. A removable safety cover for a manhole in a thick- Walled top slab of a subterranean catch basin or the like, comprising a cover plate having peripheral support on the top of the circumferential ledge of the manhole in the top slab, vertical brackets secured to the bottom of said plate and extending substantially below the same, and clamping arms mounted at the lower ends of said brackets and substantially spaced from said plate, said arms extending horizontally outward to resiliently engage under and hold to the lower side of said manhole ledge to clamp and hold the cover in place on the top of the slab and manhole, one of said brackets having a vertical portion corresponding to the thickness of said ledge and with horizontally projecting bottom and intermediate portions having vertically aligned apertures therein, the cover having a keyhole in line with said apertures, a vertically movable and rotatable stem mounted in said apertures, the clamping arm of said bracket being secured to the lower end of said stem beneath said bottom portion of the bracket, a coiled spring on said stem urging it upwardly, the clamping arm having an upstanding portion engaging said bracket in the raised clamping position of the arm to prevent rotation thereof, and a key insertable in the keyhole and temporarily engaging said stem manually to depress said stem and rotate the clamping arm.

8. A removable safety cover for a manhole in a thickwalled top slab of a subterranean catch basin or the like, comprising a cover plate having peripheral support on the top of the circumferential ledge of the manhole in the top slab, vertical brackets secured to the bottom of said plate and extending substantially below the same, and clamping arms mounted at the lower ends of said brackets and substantially spaced from said plate, said arms extending horizontally outward to resiliently engage under and hold to the lower side of said manhole ledge to clamp and hold the cover in place on the top of the slab and manhole, one of said brackets having a vertical portion corresponding to the thickness of the ledge and with horizontally projecting bottom and intermediate portions having vertically aligned apertures therein, the cover having a keyhole in line with said apertures, a vertically movable and rotatable stem mounted in said apertures, the clamping arm of said bracket being secured to the lower end of said stem beneath the bottom portion of the bracket, a coiled spring on said stem urging it upwardly, interengaging parts on the arm and said bottom portion in the clamping position of the arm and locking same against rotation, and a separable key insertable through said keyhole to grip said stem to depress and unlock the arm and to rotate it, said key having a lateral projection engaging under the cover when depressed and turned to an unlocked position thus preventing its withdrawal, said plate having a recess into which said projection is raised by said spring when the key is turned to the iinal locked position.

9. A safety manhole cover to be secured to iianged manholes comprising a cover plate to peripherally engage such a manhole, circumferentially spaced resilient clamps secured to the underside of said plate to resiliently engage such a iiange, the clamp on one side of the center of said plate having a rotatable stern resiliently urged toward said plate, a locking member engageable with such a ilange fixed to said stem and rotatable therewith, and a separable key engageable with said stem to effect axial movement and rotation thereof, said plate having a key receiving aperture therein in axial alignment with said stem.

10. A safety manhole cover to be secured to flanged manholes comprising a cover plate having peripheral support to engage the liange of such a manhole, circumferentially spaced resilient adjustable clamps on the underside of said plate for engaging such a flange, the clamp on one side of the center of the cover having a rotatable stem resiliently urged toward said plate, a locking member xed to the lower part of said stem and rotatable therewith, and a separable key engageable with said stem to effect axial movement and rotation thereof, said plate having an aperture therethrough in axial alignment with said stem whereby said key may be inserted through said aperture to rotate said stem to move said locking member between a disengaged position and a position whereby the locking member resiliently engages such a ange.

11. A safety manhole cover to be secured to flanged manholes comprising a cover plate to peripherally engage such a manhole, circumferentially spaced resilient clamps secured to the underside of said plate to resiliently engage such a ange, the clamp on one side of the center of said plate having a rotatable stem resiliently urged toward said plate, a locking member engageable with such a flange secured to said stem and rotatable therewith, a separable key engageable with said stem to effect axial movement and rotation thereof, said plate having a key receiving aperture therein in axial alignment with said stem, means to prevent removal of said key for all positions of said locking member other than the flange engaging position, and means to prevent rotation of said stem unless said stem is axially moved by said key.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,210,197 OConnor Dec. 26, 1916 1,224,534 Hall May 1, 1917 1,250,495 Pandolfo Dec. 18, 1917 1,430,760 Schley Oct. 3, 1922 1,553,639 Sherman Sept. 15, 1925 1,784,551 Smith Dec. 9, 1930 1,902,731 Sherman Mar. 2l, 1933 2,031,885 Gredell Feb. 25, 1936 2,246,344 Calderwood June 17, 1941 

